The present invention relates to a door lock, and more particularly to such a door lock which is strong, safe, and practical in use.
A variety of door locks have been disclosed for use to lock a door. FIG. 1 illustrates a door lock for this purpose. This structure of door lock comprises an external lock body and an internal lock body respectively mounted on the door body of the door at two opposite sides, two coupling rods mounted inside the door body and connected between the lock cylinder of the external lock body and the internal lock body, and a locking bolt controlled to lock/unlock the door. The internal lock body has a rotary handle that can be rotated to lock/unlock the locking bolt. This structure of door lock has numberous drawbacks as outlined hereinafter. One drawback of this structure of door lock is its complicated installation procedure. Another drawback of this structure of door lock is that the external lock body tends to be broken and disconnected from the coupling rods by violence. Still another drawback of this structure of door lock is that the internal lock body can not stop the spindle from rotation, and the spindle of the lock cylinder can easily be rotated with tool means to unlock the locking bolt. Furthermore, because the rotary handle of the internal lock body does not keep the internal lock body mounting screws from sight, the internal lock body mounting screws are exposed to the outside, causing the sense of beauty of the door to be destroyed.
The present invention has been accomplished to provide a door lock which eliminates the aforesaid drawbacks. According to an internal locking unit holding a lock cylinder, an internal locking unit, and a locking bolt unit controlled by the lock cylinder to lock/unlock the door, wherein said internal locking unit is controlled by a sliding knob to lock/unlock the spindle of the lock cylinder. According to another aspect of the present invention, two C-shaped reinforcing plates are respectively mounted on outer face panel and inner face panel of the door body of the door at an inner side, and respectively connected to the casing of the external locking unit and the circular base block of the internal locking unit by mounting screws to reinforce the strength of the door lock. According to still another aspect of the present invention, the internal locking unit has a rotary cover covered on the circular base block to keep the respective mounting screws from sight.